Summary While in cruising flight at night, the Cessna 172, C-GXSD, serial No. 17261853, experienced a complete loss of electrical power just south of Montreal, Quebec. The pilot decided to terminate the flight and land at the St-Hubert Airport, Quebec, on runway 24L. While the Cessna 172 was landing, the Katana, C-GADA, serial No. 10281, with an instructor and a student on board, was cleared to take off on St-Hubert Airport runway 06R. The two aircraft collided just west of taxiway Foxtrot. Both aircraft were extensively damaged. The three occupants sustained minor injuries. Ce rapport est galement disponible en franais. Other Factual Information The pilot of the Cessna 172, the only occupant on board, was on a training flight. All current maps and publications necessary for the flight were carried on board the aircraft. The aircraft took off in daylight from Qubec Airport under visual flight rules (VFR) and the pilot was planning to return there that same night. Stops were planned at the airports at Saint-Jean, Quebec, and then Winchester, Ontario. At 1847 eastern standard time (EST)(1), the pilot reported to the Montreal area control centre (ACC) that he was just west of the terminal control area at 3 000 feet altitude. The satellite terminal controller asked him to select transponder code 5200 and provided him with the altimeter setting. After the pilot acknowledged, the controller asked him to avoid the terminal control area by bypassing it to the south, passing over Valleyfield, Quebec, and flying over the Saint-Jean very high frequency (VHF) omnidirectional range (VOR) before continuing his flight to Qubec. At 1904, the pilot informed the ACC that he wanted to avoid the Saint-Jean control zone and would pass over Beloeil, Quebec. This was the last communication received from the pilot. No irregularity was reported during these communications. However, during the flight, the pilot observed that the ammeter was showing a continuous rate of discharge, indicating low voltage in the electrical system. The radar picked up the aircraft's signals at 3 000 feet above sea level (asl) while it was continuing its flight in Class E controlled airspace on the agreed track. In Class E controlled airspace, air traffic control (ATC) separation is provided only to aircraft operating in instrument flight rules (IFR). There are no special requirements for VFR. At 1907, at the end of twilight, about 13 nautical miles (nm) west of the Saint-Jean VOR, the transponder began to transmit intermittently until ceasing to reply less than one minute later. Thereafter, no further secondary radar returns were recorded. At about the same time, the aircraft's radios began to crackle. The pilot tried unsuccessfully to communicate with the ACC. Recognizing that two-way communication was broken, he adjusted his transponder on code 7600 to alert ATC to the situation as per regulations. The emergency code, however, was not picked up by the air traffic services (ATS) radar. Shortly thereafter, the lighting in the cabin dimmed until the lights went out. The aircraft experienced a complete loss of electrical power 24 nm from the St-Hubert Airport and 14 nm from the Saint-Jean Airport. When the pilot realized that the electrical system had failed, he decided to land on runway 24L at St-Hubert Airport, although Saint-Jean Airport was 10 nm closer to his position. His decision was based on his uncertainty about the hours of operation of the Saint-Jean tower, which in fact closed at 2100, and on his belief that the ATS radar would continue to track the flight. The radar did continue to pick up the aircraft's target, but in primary mode only. The aircraft remained on course between the St-Hubert and the Saint-Jean control zones and appeared to be heading towards Beloeil as planned. The emergency procedure to be followed by a pilot to alert radar stations when in distress and unable to establish radio contact is to fly a left-hand triangular pattern twice with two-minute legs, resume course and repeat the procedure at 20-minute intervals. When the aircraft was in Class E airspace, the terminal controller tried five times between 1913:34 and 1915:57 to contact the Cessna 172, but without any reply. There are no specific instructions to be followed by a controller when a VFR aircraft operating in Class E airspace no longer replies to the transponder signal and stops communicating on the ATC frequency. In Class E airspace, the pilot could leave the frequency and turn off his transponder without advising the controller; however, in VFR, it is customary to adjust the transponder to reply to code 1200. At about 1918, the Cessna 172 entered St-Hubert Class D airspace, extending from 2 000 feet to 6 000 feet asl. Class D airspace is a controlled airspace within which both IFR and VFR flights are permitted, but VFR flights must establish two-way communication with the appropriate ATC agency before entering the airspace. Furthermore, in the St-Hubert Class D airspace, the aircraft's transponder had to be on. ATC separation is provided only to IFR aircraft, but other aircraft will be provided with traffic information. At 1923:03, the controller tried once again unsuccessfully to contact the Cessna 172, which was still in Class D airspace and flying less than 4 nm from the St-Hubert control zone. This was the last attempt at communication with the Cessna 172 made by the controller. According to the ATS Manual of Operations (MANOPS), if a controller has reason to believe that an aircraft has experienced a radio failure, he must inform the appropriate radar units of the circumstances and request them to watch for the appearance of a special secondary surveillance radar (SSR) code or a triangular distress pattern. The radar recording indicates that the pilot made a 90-degree left turn at 1924 over Saint-Mathias Airport and then entered the St-Hubert control zone at 1927:12. There were two aircraft in the control zone: one had just taken off from runway 06R, and the other was turning on the right-hand base leg for runway 06R. Two minutes later, at 1929:23, the Cessna 172 reached the final leg of runway 24L 2 nm from the threshold at a speed of 70 knots and then vanished from the ATS radar screen. The aircraft landed midway on the runway at about 1931. A limited quantity of radar returns of the Cessna 172 was recorded intermittently in the control zone. The radar detected the Cessna 172 at seven intervals; the primary target appeared for between 5 and 14 seconds, then disappeared for between 4 and 23 seconds. More than half of the returns were of poor quality and appeared as a point. The radar floor was about 900 feet asl in this area. After ensuring that runway 06R and the runway centre line were clear, the airport controller cleared the Katana's pilot to take off. The Katana was on taxiway Tango at the time and clear of runway 06R. The student pilot began his take-off run for a night VFR training flight. The landing light, navigation lights and strobe light were lit. During the take-off roll at about 55 knots, the Katana's instructor saw the Cessna 172 rolling in the opposite direction a few metres ahead of him; to avoid collision, he pulled on the stick to pass over the Cessna. The Katana struck the roof of the Cessna 172 with its landing gear and then crashed on the runway, coming to a stop on its belly on taxiway Foxtrot. The collision occurred 950 feet from the runway threshold, 45 seconds after the Katana received clearance to take off. The weather conditions were suitable for visual flight, the wind was calm, and there was no visibility restriction. St-Hubert Airport is certified and equipped with a control tower, which was in operation with the required personnel at the time of the occurrence. A controller and a supervisor were on duty. The tower was equipped with a radar screen. Airport controllers do not use radar data to provide aircraft separation, but do use them to locate the position of aircraft. Runway 06R/24L is 3 920 feet long and 100 feet wide; it was not equipped with approach lights, which would have helped to determine the runway in use. According to the airport operations manual, the City of St-Hubert fire department serves as the first respondent in airport emergencies. As the airport does not handle any scheduled flight, the response-time standards do not apply. The emergency vehicles of the engine manufacturer Pratt Whitney, which is located on the airport, arrived at the accident site at 1941, followed one minute later by those of the City of St-Hubert. The insufficient rate of charge shown on the ammeter warned the pilot that the alternator was no longer supplying power, and that only the battery was suppling the aircraft's electrical circuits. The procedure to follow, published in section III of the Cessna 172's aircraft operating manual (AOM), was first to turn off the alternator to reduce energy expenditure due to its excitation field circuit. The AOM then recommends to decrease consumption by cutting power to non-essential equipment and land as soon as practical. According to the aircraft manufacturer, the battery can normally supply power to essential equipment for about two hours. As the pilot did not know that a low-voltage indication meant an electrical power failure in the direct current system, he did not follow the aircraft manufacturer's recommended procedure. He thought that the red over-voltage warning light illuminated in the event of an alternator malfunction. In fact, the over-voltage light illuminates only after the over-voltage sensor has detected an over-voltage and shut down the alternator. The pilot did not consult a checklist or the AOM on the flight. Although the communication failure occurred within Class E airspace outside the St-Hubert control zone, the pilot could enter the zone without clearance and continue VFR flight. However, when landing at St-Hubert Airport, he had to follow the arrival procedures for no-radio (NORDO) aircraft. The pilot had to fly over the airport at an altitude at least 500 feet above the circuit height, then descend to circuit height in the upwind area of the active runway. He then had to join the crosswind leg abeam a point approximately midway between each end of the runway and enter the circuit on the downwind leg. He had to constantly be alert for visible signals to obtain clearance to land. The pilot was not very familiar with this procedure. The pilots of the Cessna 172 and the Katana were certified and qualified for the flights in accordance with existing regulations. The pilot of the Cessna 172 held a private pilot licence and had a total of 120 hours' flight time; he was in the process of obtaining a commercial pilot licence. He had obtained his night rating on 27 January 1998. The Katana's pilot had obtained his commercial pilot licence on 10 January 1997 and his flight instructor rating on 11 April 1997. The Katana was certified, equipped and maintained in accordance with existing regulations and approved procedures. Transport Air bought the Cessna 172 in November 1997. The aircraft had a total of 2 083 hours' flight time. Before returning the aircraft to service at the flying school, the operator modified the avionic system. The operator installed new radios, a VOR/ILS indicator and a transponder. It also changed the alternator belt. The alternator field cable connector was also replaced on 17 December 1997. The aircraft was returned to service on 20 December 1997. After the return to service of the Cessna 172, three periodic inspections were carried out. On 22 January 1998, in a 50-hour overhaul, the battery was recharged. On 07 February 1998, the Cessna 172 underwent a 100-hour overhaul, and on 22 February, a 50-hour inspection was carried out. In these three inspections, the electrical wiring was checked, and no irregularity was found. At the time of the accident, the aircraft had accumulated about six hours' flight time since the last 50-hour inspection. The aircraft was certified and equipped in accordance with existing regulations. Examination of the wreckage revealed that the alternator positive-terminal cable was heavily damaged. Only 7 of the 133 strands of the cable were supplying power to the aircraft's electrical system at the time of the accident. The TSB Engineering Laboratory determined that, in all likelihood, fatigue loads due to reverse bending of the cable caused gradual wear and the failure of some hundred strands near the terminal. The remaining strands then fused when the electrical load exceeded their capacity. Federal Aviation Administration Advisory Circular AC43-13-1A, Section 7, Chapter 515, sets out the installation standards for electrical cables. To reduce fatigue loads, the bending radius of a cable near a connector may not be less than three times its outer diameter. In this instance, as the cable had a diameter of 0.25 inch, the bending radius had to be at least 0.75 inch.